Rustoleum rattle can paint and primer in one. I did scuff the whole thing with a scotchbrite roloc to give it surface tension. Only took two coats. I thought about priming it and painting it base coat with clear but that stuff is expensive. For this use the Rustoleum looks great. I wouldn't have had to pay for the paint, but it didn't really call for it.
I thought about using a torsion type spring used for car trunk lids so it would pop open. I would have ran a cable up the stairs and hid a handle behind the railing so I could open it a few steps before I got to it. I thought that would be overkill, plus I'm lazy.